1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. We want to wish everyone a healthy, happy New Year, full of joy and success. God bless you, and thank you for supporting The Hobby-Machinist.

    Dismiss Notice

Information on Heat Treating Ovens

Discussion in 'METAL FINISHING, CUTTING & WORKING' started by Nels, Apr 28, 2013.

  1. Nels

    Nels United States Founder Staff Member H-M Supporter-Premium

    Likes Received:
    683
    Trophy Points:
    113
    Location:
    Eastern Queens, NY
    City:
    Eastern Queens
    State:
    New York
  2. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

    Likes Received:
    1,177
    Trophy Points:
    113
    Location:
    Victoria, Texas
    City:
    Victoria
    State:
    Texas
    Nice picture Nelson
     
  3. pdentrem

    pdentrem Active User Active Member

    Likes Received:
    126
    Trophy Points:
    63
    City:
    Niagara Region South
    State:
    Ontario
    Interesting builds you found there, Nelson.
    I agree with the comments of using a plug door to help seal. The commercial unit we have, uses that method and does not require any gasket.
    Good reading.
    Pierre
     
  4. Ray C

    Ray C United States Moderator Staff Member Moderator

    Likes Received:
    40
    Trophy Points:
    48
    City:
    Crofton
    State:
    Maryland
    Obviously I got pretty carried-away with my thread on the home-built heat box... Sorry about that... The topic is pretty fascinating all-around to me. I loved thermodynamics and took several advanced courses in it way back when. My old college won a research grant with the DoD to build (on-site) one of the most advanced wind tunnels in existence at the time. I did some work on the air dryers and it was pure thermo. Big stuff -so big, the power company could not supply enough power so several on-site multi-megawatt generators were needed. -I digress... Anyhow, when building the furnace box, I re-did all the thermo calculations just to see if I still knew how. I just finishing researching heating element wire and ordered some different wire and will "roll my own". There's a lot more there than what meets the eye...

    Then, there's the whole topic of metallurgy related to heat treating. Even more fascinating stuff... It never ends.


    Ray
     
  5. greenhornet-1

    greenhornet-1 United States Active User Active Member

    Likes Received:
    0
    Trophy Points:
    6
    City:
    Appomattox
    State:
    Virginia
    Thanks for the info on these ovens. I think i need to build one!
     
  6. leadunderpressure

    leadunderpressure United States Active User Active Member

    Likes Received:
    0
    Trophy Points:
    16
    City:
    Sussex
    State:
    New Jersey
    What's the top end required for a heat treat furnace? Can you use the same furnace to heat a crucible for casting or is that not recommended?


    Sent from my iPad using Tapatalk HD
     
  7. Ray C

    Ray C United States Moderator Staff Member Moderator

    Likes Received:
    40
    Trophy Points:
    48
    City:
    Crofton
    State:
    Maryland
    Top end is about 2200F and that is for a few types of air-cooled tool steel; however some of the A-type steels are down in the 1800F range. More commonly, 1500 to 1650F is needed for low, medium and high carbon steels and alloys. Most of my work is done at 1550 and 1575F. BTW, these are austentizing temperatures, not melting temperatures.

    In addition to a decent heat treat oven, you need either a visual spectrometer or high-end IR thermometer. For accurate/critical treating you cannot just look at the color or use a magnet to determine proper phase changes. You also need some method of oxygen deprivation. I've had good luck using a small burn-off piece along with argon gas flooding. Stainless steel foil is very expensive and error prone (not to mention, sharp as a razor and hard to handle). And of course, proper safety equipment.

    Be apprised that at these temperatures, you are not playing games. The kinds of burns you get from this cause primal screams and foaming at the mouth and nostrils -long before you get the first cuss-words out of your mouth...

    As far as casting (which I have no experience) I tend to think these temps are best for aluminum and other metals in the temperature range mentioned above. The ovens I'm referring to are heated with nicrome or kanthal wire. Nicrome tops out with a usable temperature of about 2000F and kanthal will go up to 2200F (usable oven temp). Beyond that, you need to get into carbon arc and there's not enough electricity in your service panel to get to high volume melting of around 2600F for steel forging.

    Here's a reference chart of melting temperatures: http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html

    PS: I have a sizeable thread here about a shop made heat treating furnace and I do a good bit of it with good results.

    Ray


     

Share This Page